Two new bisindole alkaloids, alstomacrophylline and alstomacroline, have been isolated from the root bark of Alstonia macrophylla, along with six known alkaloids, alstonerine, alstophylline, macrocarpamine, alstoumerine, 20-epi-antirhine and villastonine N-oxide. The monomeric indole alkaloid, 20-epi-antirhine, has been isolated for the first time from this species. Structures of the alkaloids were determined by spectroscopic methods, especially 2D NMR. (C) 1997 Elsevier Science Ltd.